Github project to automatically build Arduino libraries published for ESP32

[VojtechBartoska]

Set up automated build of Arduino libraries and report build regressions.

Source of libraries: https://www.arduinolibraries.info/architectures/esp32

[VojtechBartoska]

This issue relates to #7130

[VojtechBartoska]

This feature was implemented in those related PRs:

• [CI] External libraries compilation test #8003
• CI External Libraries Test - Results comment fix #8035
• [CI] External Libraries Test - Results file relocation #8072
• [CI] External Libraries Test - Results file push fix #8089
• Add MFRC522 and WS2812FX library to External library testing #8145
• External library test - Example change for WS2812FX lib #8146

The result are available here: https://github.com/espressif/arduino-esp32/blob/gh-pages/LIBRARIES_TEST.md

Documentation about this CI feature is available here: https://docs.espressif.com/projects/arduino-esp32/en/latest/external_libraries_test.html